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Example: Java App Engine standard environment
This example is anApp Engineapplication, written in
Java, that writes some "hello world" greetings to a Bigtable
table and reads them back. The application runs on Google Cloud in the
App Enginestandard environment. The application
uses theJava 8 runtime. The code for this application is in the GitHub
repositoryGoogleCloudPlatform/java-docs-samples, in the
directoryappengine-java8/bigtable.
Overview of the code sample
The code sample includes the following classes:
BigtableHelper, which provides a connection to
Bigtable.
BigtableHelperprovides a method to create a connection to
Bigtable. It also caches the connection and provides a method that
will retrieve the cached connection if it exists. Creating a connection is a
relatively expensive operation, so as a best practice you should always create a
single connection and reuse it.
publicstaticvoidconnect()throwsIOException{if(PROJECT_ID==null||INSTANCE_ID==null){if(sc!=null){sc.log("environment variables BIGTABLE_PROJECT, and BIGTABLE_INSTANCE need to be defined.");}return;}connection=BigtableConfiguration.connect(PROJECT_ID,INSTANCE_ID);}/*** Get the shared connection to Cloud Bigtable.** @return the connection*/publicstaticConnectiongetConnection(){if(connection==null){try{connect();}catch(IOExceptione){if(sc!=null){sc.log("connect ",e);}}}if(connection==null){if(sc!=null){sc.log("BigtableHelper-No Connection");}}returnconnection;}
BigtableHelloWorld
BigtableHelloWorldis used to write a series of greetings to
Bigtable, read the greetings, and then display them. The class
gets a Bigtable connection fromBigtableHelper, uses the
connection to get aTableobject, which lets you to read and write values,
then uses theTableobject to write to and read from the table.
/*** A minimal application that connects to Cloud Bigtable using the native HBase API and performs* some basic operations.*/publicclassBigtableHelloWorld{// Refer to table metadata names by byte array in the HBase APIprivatestaticfinalbyte[]TABLE_NAME=Bytes.toBytes("Hello-Bigtable");privatestaticfinalbyte[]COLUMN_FAMILY_NAME=Bytes.toBytes("cf1");privatestaticfinalbyte[]COLUMN_NAME=Bytes.toBytes("greeting");// Write some friendly greetings to Cloud BigtableprivatestaticfinalString[]GREETINGS={"Hello World!","Hello Cloud Bigtable!","Hello HBase!"};/*** Create a table -- first time only.** @param connection to Bigtable* @return the status*/publicstaticStringcreate(Connectionconnection){try{// The admin API lets us create, manage and delete tablesAdminadmin=connection.getAdmin();// Create a table with a single column familyHTableDescriptordescriptor=newHTableDescriptor(TableName.valueOf(TABLE_NAME));descriptor.addFamily(newHColumnDescriptor(COLUMN_FAMILY_NAME));admin.createTable(descriptor);}catch(IOExceptione){return"Table exists.";}return"Create table "+Bytes.toString(TABLE_NAME);}/** Connects to Cloud Bigtable, runs some basic operations and prints the results. */publicstaticStringdoHelloWorld(){StringBuilderresult=newStringBuilder();// Create the Bigtable connection, use try-with-resources to make sure it gets closedConnectionconnection=BigtableHelper.getConnection();result.append(create(connection));result.append("<br><br>");try(Tabletable=connection.getTable(TableName.valueOf(TABLE_NAME))){// Retrieve the table we just created so we can do some reads and writes// Write some rows to the tableresult.append("Write some greetings to the table<br>");for(inti=0;i<GREETINGS.length;i++){// Each row has a unique row key.//// Note: This example uses sequential numeric IDs for simplicity, but// this can result in poor performance in a production application.// Since rows are stored in sorted order by key, sequential keys can// result in poor distribution of operations across nodes.//// For more information about how to design a Bigtable schema for the// best performance, see the documentation://// https://cloud.google.com/bigtable/docs/schema-designStringrowKey="greeting"+i;// Put a single row into the table. We could also pass a list of Puts to write a batch.Putput=newPut(Bytes.toBytes(rowKey));put.addColumn(COLUMN_FAMILY_NAME,COLUMN_NAME,Bytes.toBytes(GREETINGS[i]));table.put(put);}// Get the first greeting by row keyStringrowKey="greeting0";ResultgetResult=table.get(newGet(Bytes.toBytes(rowKey)));Stringgreeting=Bytes.toString(getResult.getValue(COLUMN_FAMILY_NAME,COLUMN_NAME));result.append("Get a single greeting by row key<br>");result.append(" ");result.append(rowKey);result.append("= ");result.append(greeting);result.append("<br>");// Now scan across all rows.Scanscan=newScan();result.append("Scan for all greetings:");ResultScannerscanner=table.getScanner(scan);for(Resultrow:scanner){byte[]valueBytes=row.getValue(COLUMN_FAMILY_NAME,COLUMN_NAME);result.append(" ");result.append(Bytes.toString(valueBytes));result.append("<br>");}}catch(IOExceptione){result.append("Exception while running HelloWorld: "+e.getMessage()+"<br>");result.append(e.toString());returnresult.toString();}returnresult.toString();}}
[[["Easy to understand","easyToUnderstand","thumb-up"],["Solved my problem","solvedMyProblem","thumb-up"],["Other","otherUp","thumb-up"]],[["Hard to understand","hardToUnderstand","thumb-down"],["Incorrect information or sample code","incorrectInformationOrSampleCode","thumb-down"],["Missing the information/samples I need","missingTheInformationSamplesINeed","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-09-04 UTC."],[[["\u003cp\u003eThis Java application demonstrates how to interact with a Bigtable database from the Google App Engine standard environment using the Java 8 runtime.\u003c/p\u003e\n"],["\u003cp\u003eThe \u003ccode\u003eBigtableHelper\u003c/code\u003e class manages the connection to Bigtable, caching it for reuse to improve performance.\u003c/p\u003e\n"],["\u003cp\u003eThe \u003ccode\u003eBigtableHelloWorld\u003c/code\u003e class handles writing greetings to a Bigtable table, reading them back, and displaying them.\u003c/p\u003e\n"],["\u003cp\u003eThe code utilizes the HBase API to create a table, write rows with column family, and scan/read the values from the table.\u003c/p\u003e\n"],["\u003cp\u003eThe example is intended to showcase the basic operations with Bigtable, and recommends referring to the documentation on schema-design for better performance in production applications.\u003c/p\u003e\n"]]],[],null,["Example: Java App Engine standard environment\n\nThis example is an [App Engine](/appengine) application, written in\nJava, that writes some \"hello world\" greetings to a Bigtable\ntable and reads them back. The application runs on Google Cloud in the\nApp Engine [standard environment](/appengine/docs/standard). The application\nuses the [Java 8 runtime](/appengine/docs/standard/java/runtime-java8). The code for this application is in the GitHub\nrepository [GoogleCloudPlatform/java-docs-samples](https://github.com/GoogleCloudPlatform/java-docs-samples), in the\ndirectory `appengine-java8/bigtable`.\n\nOverview of the code sample\n\nThe code sample includes the following classes:\n\n- [`BigtableHelper`](https://github.com/GoogleCloudPlatform/java-docs-samples/blob/master/appengine-java8/bigtable/src/main/java/com/example/bigtable/BigtableHelper.java), which provides a connection to Bigtable.\n- [`BigtableHelloWorld`](https://github.com/GoogleCloudPlatform/java-docs-samples/blob/master/appengine-java8/bigtable/src/main/java/com/example/bigtable/BigtableHelloWorld.java), which writes to and reads from Bigtable.\n\nBigtableHelper\n\n`BigtableHelper` provides a method to create a connection to\nBigtable. It also caches the connection and provides a method that\nwill retrieve the cached connection if it exists. Creating a connection is a\nrelatively expensive operation, so as a best practice you should always create a\nsingle connection and reuse it. \n\n public static void connect() throws IOException {\n\n if (PROJECT_ID == null || INSTANCE_ID == null) {\n if (sc != null) {\n sc.log(\"environment variables BIGTABLE_PROJECT, and BIGTABLE_INSTANCE need to be defined.\");\n }\n return;\n }\n\n connection = BigtableConfiguration.connect(PROJECT_ID, INSTANCE_ID);\n }\n\n /**\n * Get the shared connection to Cloud Bigtable.\n *\n * @return the connection\n */\n public static Connection getConnection() {\n if (connection == null) {\n try {\n connect();\n } catch (IOException e) {\n if (sc != null) {\n sc.log(\"connect \", e);\n }\n }\n }\n if (connection == null) {\n if (sc != null) {\n sc.log(\"BigtableHelper-No Connection\");\n }\n }\n return connection;\n }\n\nBigtableHelloWorld\n\n`BigtableHelloWorld` is used to write a series of greetings to\nBigtable, read the greetings, and then display them. The class\ngets a Bigtable connection from `BigtableHelper`, uses the\nconnection to get a `Table` object, which lets you to read and write values,\nthen uses the `Table` object to write to and read from the table. \n\n\n /**\n * A minimal application that connects to Cloud Bigtable using the native HBase API and performs\n * some basic operations.\n */\n public class BigtableHelloWorld {\n\n // Refer to table metadata names by byte array in the HBase API\n private static final byte[] TABLE_NAME = Bytes.toBytes(\"Hello-Bigtable\");\n private static final byte[] COLUMN_FAMILY_NAME = Bytes.toBytes(\"cf1\");\n private static final byte[] COLUMN_NAME = Bytes.toBytes(\"greeting\");\n\n // Write some friendly greetings to Cloud Bigtable\n private static final String[] GREETINGS = {\n \"Hello World!\", \"Hello Cloud Bigtable!\", \"Hello HBase!\"\n };\n\n /**\n * Create a table -- first time only.\n *\n * @param connection to Bigtable\n * @return the status\n */\n public static String create(Connection connection) {\n try {\n // The admin API lets us create, manage and delete tables\n Admin admin = connection.getAdmin();\n\n // Create a table with a single column family\n HTableDescriptor descriptor = new HTableDescriptor(TableName.valueOf(TABLE_NAME));\n descriptor.addFamily(new HColumnDescriptor(COLUMN_FAMILY_NAME));\n\n admin.createTable(descriptor);\n } catch (IOException e) {\n return \"Table exists.\";\n }\n return \"Create table \" + Bytes.toString(TABLE_NAME);\n }\n\n /** Connects to Cloud Bigtable, runs some basic operations and prints the results. */\n public static String doHelloWorld() {\n\n StringBuilder result = new StringBuilder();\n\n // Create the Bigtable connection, use try-with-resources to make sure it gets closed\n Connection connection = BigtableHelper.getConnection();\n result.append(create(connection));\n result.append(\"\u003cbr\u003e\u003cbr\u003e\");\n try (Table table = connection.getTable(TableName.valueOf(TABLE_NAME))) {\n\n // Retrieve the table we just created so we can do some reads and writes\n\n // Write some rows to the table\n result.append(\"Write some greetings to the table\u003cbr\u003e\");\n for (int i = 0; i \u003c GREETINGS.length; i++) {\n // Each row has a unique row key.\n //\n // Note: This example uses sequential numeric IDs for simplicity, but\n // this can result in poor performance in a production application.\n // Since rows are stored in sorted order by key, sequential keys can\n // result in poor distribution of operations across nodes.\n //\n // For more information about how to design a Bigtable schema for the\n // best performance, see the documentation:\n //\n // https://cloud.google.com/bigtable/docs/schema-design\n String rowKey = \"greeting\" + i;\n\n // Put a single row into the table. We could also pass a list of Puts to write a batch.\n Put put = new Put(Bytes.toBytes(rowKey));\n put.addColumn(COLUMN_FAMILY_NAME, COLUMN_NAME, Bytes.toBytes(GREETINGS[i]));\n table.put(put);\n }\n\n // Get the first greeting by row key\n String rowKey = \"greeting0\";\n Result getResult = table.get(new Get(Bytes.toBytes(rowKey)));\n String greeting = Bytes.toString(getResult.getValue(COLUMN_FAMILY_NAME, COLUMN_NAME));\n result.append(\"Get a single greeting by row key\u003cbr\u003e\");\n\n result.append(\" \");\n result.append(rowKey);\n result.append(\"= \");\n result.append(greeting);\n result.append(\"\u003cbr\u003e\");\n\n // Now scan across all rows.\n Scan scan = new Scan();\n\n result.append(\"Scan for all greetings:\");\n ResultScanner scanner = table.getScanner(scan);\n for (Result row : scanner) {\n byte[] valueBytes = row.getValue(COLUMN_FAMILY_NAME, COLUMN_NAME);\n result.append(\" \");\n result.append(Bytes.toString(valueBytes));\n result.append(\"\u003cbr\u003e\");\n }\n\n } catch (IOException e) {\n result.append(\"Exception while running HelloWorld: \" + e.getMessage() + \"\u003cbr\u003e\");\n result.append(e.toString());\n return result.toString();\n }\n\n return result.toString();\n }\n }"]]
